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Diving Deeper: Harmful Algal Bloom Forecasting

Episode 53 (November 21, 2013)

HOST: Today on Diving Deeper we'll talk forecasting. We're all familiar with weather forecasts and even tides, but did you know scientists forecast so much more than that?

Today, we'll be joined by Allison Allen who is part of a team of scientists working on forecasting harmful algal blooms. Hi Allison, thanks for joining us today!

ALLISON ALLEN: Thanks for inviting me here today Kate.

HOST: So Allie, let's start by defining harmful algal blooms for our audience. What exactly is a harmful algal bloom?

ALLISON ALLEN: There's many different types and species of algae and not all of them are harmful. In fact algae are really important to marine and freshwater ecosystems and most species of algae are not harmful. But algal blooms occur when conditions are favorable for rapid growth for one reason or another of a particular species and sometimes these blooms can have harmful effects. So blooms are considered harmful when they have a negative impact on either people or the environment, but a very small percentage of those blooms are actually toxic, actually less than one percent of those.

So, when most people think of what a harmful algal bloom is, they think of discolored water - red, brown, yellow, maybe it's slimy, maybe it smells bad, sometimes it can even make the water taste bad.

HOST: And besides the fact that harmful algal blooms can cause the water to change color and look bad like you've just mentioned, are there other reasons we should be concerned about these?

ALLISON ALLEN: There are. Harmful algal blooms or HABs can cause a wide range of impacts to human and ecosystem health. Those impacts are really the reasons that we pay such close attention to these events. HABs can cause toxins and they can kill fish, mammals, and birds and cause a range of illness in people. Sometimes we see large fish kill events when we have a harmful algal bloom or we might see what we call an unusual marine mammal mortality. In fact HABs are the major cause of unusual mortality events which may mean a dramatic increase in dolphin deaths or even endangered species such as manatees we see in some of these events.

HABs can last for several months and then even after that they can remain in the tissues of shellfish for months after that so there's long-lasting impacts. And in terms of impacts to people as an example, the species Karenia brevis in the Gulf of Mexico causes an aerosol that can cause respiratory distress in people, which makes people feel similar to having asthma. In fact, there are a number of increases in ER visits when there's a major bloom in Florida. In the Great Lakes for instance, recurring blooms of green algae or cyanobacteria take place nearly every year and those blooms are of concern to the drinking water, which then must be treated, when they're having one of those blooms.

And even blooms of non-harmful algae can cause dramatic ecosystem impacts such as depleting the oxygen in the water, blocking sunlight from benthic organisms, or even by clogging the gills of fish. And as a dog lover myself, one of the things that people don't always think about is impacts to dogs that can get sick from swimming in water that is having an algae bloom. In short, harmful algal blooms can have significant economic and cultural consequences too and all of these impacts really just stress the importance of understanding HABs and developing the tools to forecast their impacts.

HOST: Thanks Allie, you've given us quite a list of impacts so this should answer anybody's questions, if you've ever been wondering before if we should be concerned about harmful algal blooms, that definitely yes we should. My next question is, where do harmful algal blooms typically occur?

ALLISON ALLEN: Harmful algal blooms really occur in all coastal states in the U.S. The specific nature of the impacts varies depending on the species of concern and a number of other factors. HABs also occur in freshwater so the Great Lakes is a great example of that and then there's also particular seasons when HABs are more likely to occur in a specific area.

HOST: And you mentioned before a little bit about some of the economic impacts that we might see from harmful algal blooms. Do we have statistics on what a bloom can cost a community? And what this economic impact is?

ALLISON ALLEN: We do and it's pretty dramatic. So a coastal HAB event has been estimated to cost over $100 million a year in economic impacts, which is substantial. The impact is especially dramatic for coastal communities that depend on seafood and tourism industries. HABs can disrupt commercial and recreational seafood harvesting. And in fact the impacts to tourism don't end at the beach or waterfront properties and that's what sometimes people forget, but all service related industries in a coastal community can be impacted, you know, people don't go to the restaurants. And areas impacted by regular blooms, such as those causing discolored or foul-smelling water, may even see long-term impacts in property values over time.

HOST: And Allie, for our listeners who don't live in a coastal city that is prone to harmful algal blooms, how does this affect them?

ALLISON ALLEN: Well, you don't have to live at the coast to appreciate seafood, right? So eating shellfish that has become contaminated from a HAB can cause a range of illnesses or even in rare instances, death. It doesn't mean of course that the seafood that we all eat is unsafe, there's rigorous monitoring programs in place to ensure that all legally-harvested seafood is safe for human consumption, but beyond just the impact to shellfish and fish, people who don't live in a coastal city can be impacted if they're planning a vacation to a location that's routinely impacted by a harmful algal bloom.

While that's certainly not necessary to avoid visiting those places all together, it's important to know where to find up-to-date information on conditions to stay safe and informed. There may be times that beaches are closed and vacationers will likely want to know that information before traveling. But because these blooms are often very patchy, it's also often the case that knowing where to look can allow you not to cancel a beach day, but to find an unimpacted beach that's nearby.

HOST: So, seeing as how HABs have a huge negative impact for coastal communities, what can we do about this? Can we prepare for these events in some way?

ALLISON ALLEN: We can. Finding and measuring harmful algae has historically been difficult and labor intensive. For instance, research cruises to collect and analyze water samples, while both important and accurate, can be time and resource intensive, so it's been really important to develop methods for forecasting harmful algal blooms, particularly in the areas with the greatest ecosystem, health, and financial impacts. Advanced warning of HABs increases the options for managing these events and their impacts and it can decrease the cost of dealing with the event and the time it takes to rebound from the event as well. So to this end, NOAA is developing Harmful Algal Bloom forecasts and the forecasts are provided to state resource managers and other decision makers to take necessary action, for instance, issuing beach or shellfish bed closures.

HOST: What kind of data do you need to create one of these harmful algal bloom forecasts?

ALLISON ALLEN: HAB forecasts rely on a range of different data types. Because there's such regional difference in HAB characteristics, forecasts are really tailored to best address the issues of concern in a particular location from the information they provide to the science and the tools used to develop that forecast. For instance, in the Gulf of Mexico, ocean color is a really important component to the forecasts while in the Northeast, sea surface temperature plays a larger role as an indicator.

But in general, the type of data we use includes satellite imagery, field observations such as samples, glider data, oceanographic and atmospheric monitoring platforms such as buoys or surface current mapping technology to help us determine the location, extent, and potential for development or movement of the bloom. We also rely on a range of models and forecasts such as wind forecasts or models of transport.

HOST: And Allie, how are people involved? Is a forecast just produced automatically with computers and maybe data from satellites or do people really play a role in developing a harmful algal bloom forecast?

ALLISON ALLEN: It's a combination of all of those things, but people really play a big role. So forecasts do rely on human analysis and verification. We have a number of HAB analysts working in NOAA's Center for Operational Oceanographic Products and Services, working to put together all of the operational forecasts on a daily basis. They are working with all of the data, combining it with their own expertise to issue the best forecast. But I would mention too that the science behind the forecast is very much inter-discplinary. So you have, for instance, biologists working right alongside oceanographers to make sure the reasoning behind the forecast is accurate.

HOST: And what kind of information does a forecast provide?

ALLISON ALLEN: Our HAB forecasts, which are issued as bulletins, include information on forecasted conditions for the next three to seven days depending on whether there's an active bloom underway including information on potential or confirmed HAB events, chlorophyll levels, and the forecasted winds. The bulletins also provide forecasts for potential human impacts associated with confirmed blooms, it also provides information on the bloom size, movement, intensification, and the potential for bloom formation.

So there's different sections of the forecast that we provide. There's public conditions that are geared more towards the public, focusing on those potential health impacts while a more in-depth analysis provides the detailed information on the likely changes in the bloom over the next few days such as changes in the intensity of the event or the extent, which is more helpful for informing necessary actions such as monitoring.

HOST: Allie, who uses harmful algal bloom forecasts?

ALLISON ALLEN: These forecasts are not only used by the public who want to know if their beach will be impacted, but by a wide range of resource managers and decision makers who need to take necessary action. So, necessary action depends on the location and nature of the bloom. It might include beach or shellfish bed closures, providing information to the public on the nature of potential impacts, going to collect water samples in a particular area, or even in some cases, taking action to assist or relocate endangered species in an impacted area. Longer range, seasonal forecasts can also be quite helpful for longer-term planning such as knowing how much states need to budget for monitoring of drinking water in a given year.

So, while NOAA's not itself taking these actions. Information provided by the forecasts is critical to be able to do so.

HOST: Allie, in what regions, what parts of the U.S., do you currently have harmful algal bloom forecasts?

ALLISON ALLEN: NOAA currently has operational HAB forecasts in the Gulf of Mexico, specifically that's the west Florida shelf and then into Texas as well. There's several other forecasts under development to be transitioned to operations in the next few years and that includes the Gulf of Maine and Lake Erie.

HOST: So Allie, besides forecasting harmful algal blooms, are there other types of forecasts that NOAA is working on?

ALLISON ALLEN: NOAA's uniquely positioned to provide ecological forecast products and services. For instance, NOAA already collects huge amounts of weather and climate, oceanographic, coastal, and biological information that's ready to be assimilated into predictive systems to be able to support these forecasts. These components are the cornerstone of NOAA's collective ability to protect lives and property, enhance economic security, and meet its stewardship mandates.

So, over the past year, NOAA's really made good progress with developing an ecological forecasting program or roadmap to be able to better provide a coordinated approach to developing and delivering these ecological forecasts that best meet NOAA's science, service, and stewardship mandates.

The effort's really focusing on an initial set of priorities including harmful algal blooms, but also including hypoxia and pathogens. And when I talk about hypoxia, I'm referring to the condition of depleted oxygen in the water column and by pathogens, I'm referring to, in this case, naturally-occurring, disease-causing bacteria. So, the goal of this effort is to develop operational forecasts in these areas, similar to what exists for HAB forecasts in the Gulf of Mexico and we're looking at delivering these forecasts at a national scale, but with regional specificity and delivery needed to appropriately address specific issues.

HOST: So Allie, you started off with explaining to us why we should care about harmful algal blooms, why this is a problem, then we've moved into talking about that we can forecast these blooms to help us prepare, the kinds of data that go into these forecasts, and the information that come out of them. Can you share with us maybe an example or two of how these forecasts are being used by folks?

ALLISON ALLEN: Sure. In 2005, there was a historic bloom in New England resulting in unprecedented closures of shellfish beds. That was really to prevent paralytic shellfish poisoning in human consumers of those shellfish. So those closures alone were estimated to have an impact of $18 million in Massachusetts of lost shellfish sales and almost $5 million in Maine. So that's substantial, and so what I want to point out is just as important as the forecasts are for being able to close those shellfish beds to avoid impacts to humans, the reverse is also true that those forecasts are necessary to be able to avoid unnecessary closures, when every day of revenue lost has such a dramatic impact on the economy.

In addition, illnesses associated with the pathogen Vibrio vulnificus can be especially challenging if a physician doesn't know what to look for. And misdiagnosis can have drastic consequences if the illness isn't caught and treated in time. Just this past summer, a doctor contacted the operators of a demonstration Vibrio model in the Chesapeake Bay to confirm possible exposure to the bacteria based on where the individual had been swimming. So these are just a few examples of the impacts of these forecasts and of early detection. While we still have a long way to go to have the necessary forecasts everywhere they're needed, the need for this information and the benefit of this information is clear.

HOST: Allie, is there a way our listeners can help, really just to step up and do something to help with this problem of harmful algal blooms?

ALLISON ALLEN: Yes, there is. I mentioned earlier the need to constantly improve the science and the monitoring behind the forecasts. And there's a number of citizen science programs emerging, such as the Phytoplankton Monitoring Network, where people can get involved with monitoring coastal waters for harmful algal blooms. This particular program has over 11 years of data in some areas and that's been an invaluable resource to inform the research needed for effective forecasts. These programs really increase the number of eyes that we have on our coastal waters and allow us to better understand what is happening.

In the future, there may also be additional social media and smartphone apps to better allow the public to serve as the spotters for events such as HABs.

HOST: And Allie, as we wrap up our discussion for today, what would you like to leave our listeners with?

ALLISON ALLEN: Well, first I want to thank you for letting me join you today because I think this is an important topic for people to learn more about. But I guess the bottom line from today's discussion is that HABs can be serious events with significant and far-reaching impacts. Understanding these events is the first step in minimizing health impacts and economic losses. There's a lot of exciting work being done to improve forecasting capabilities to better inform coastal and resource management needs.

HOST: Thank Allie for joining us today on Diving Deeper and sharing with us more about NOAA's work in the field of ecological forecasting and specifically harmful algal bloom forecasting. To learn more, visit

That's all for today's show. Diving Deeper will be back in just two weeks!